Various abbreviations that appear in the specification and/or in the drawing figures are defined as follows:                3GPP third generation partnership project        ACK acknowledge        BW bandwidth        CCE control channel element        CDM code division multiplexing        CM cubic metric (measure of peak-to-average ratio of a signal)        DAI downlink assignment index        DL downlink (eNB towards UE)        eNB EUTRAN Node B (evolved Node B)        EPC evolved packet core        EUTRAN evolved UTRAN (LTE)        FDD frequency division duplex        FDMA frequency division multiple access        HARQ hybrid automatic repeat request        HO handover        ITU international telecommunications union        LTE long term evolution        LTE-A LTE-advanced        MAC medium access control        MM mobility management        MME mobility management entity        NACK not (negative) acknowledge        Node B base station        O&M operations and maintenance        OFDMA orthogonal frequency division multiple access        PDCCH physical downlink control channel        PDCP packet data convergence protocol        PDU protocol data unit        PHY physical layer        PRB physical resource block        PUCCH physical uplink control channel        PUSCH physical uplink shared channel        QPSK quadrature phase shift keying        RAN radio access network        Rel-8 LTE Release 8        RLC radio link control        RRC radio resource control        RRM radio resource management        SC-FDMA single carrier, frequency division multiple access        SDU service data unit        S-GW serving gateway        TDD time division duplex        TTI transmission time interval        UE user equipment        UL uplink (UE towards eNB)        UTRAN universal terrestrial radio access network        ZAC zero-autocorrelation (computer-search based reference signal sequences used in UL)        
The specification of a communication system known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA) is nearing completion within 3GPP. In this system the DL access technique will be OFDMA and the UL access technique will be SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.5.0 (2008-05), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (E-UTRAN); Overall description; Stage 2 (Release 8), which is attached to the priority document U.S. Provisional Patent Application No. 61/194,042 (filed Sep. 23, 2008) as Exhibit A.
In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.311, 36.312, etc.) may be seen as describing the entire Release-8 LTE system.
FIG. 8 reproduces FIG. 4 of 3GPP TS 36.300, and shows the overall architecture of the E-UTRAN system. The E-UTRAN system includes eNBs, providing the E-UTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME (Mobility Management Entity) by means of a S1-MME interface and to a Serving Gateway (S-GW) by means of a S1-U interface. The S1 interface supports a many-to-many relation between MMEs/Serving Gateways and eNBs.
The eNB hosts the following functions:
functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling);
IP header compression and encryption of user data stream;
selection of a MME at UE attachment;
routing of User Plane data towards Serving Gateway;
scheduling and transmission of paging messages (originated from the MME);
scheduling and transmission of broadcast information (originated from the MME or O&M); and
measurement and measurement reporting configuration for mobility and scheduling.
Of even greater interest herein is the evolution of LTE Rel-8 to Rel-9 and beyond, including LTE-A, and more specifically the UL/DL control channel arrangement in the LTE-A system. These further releases of 3GPP LTE are targeted towards future IMT-A systems, referred to for convenience simply as LTE-A. Of additional interest herein are local area (LA) deployment scenarios using a scalable bandwidth (of up to, for example, 100 MHz) with flexible spectrum use (FSU).
Reference can also be made to 3GPP TR 36.913, V8.0.0 (2008-06), 3rd Generation Further Advancements for E-UTRA (LTE-Advanced) (Release 8), attached to the above-referenced priority document as Exhibit B.
LTE-A will be an evolution of LTE Rel-8 system fulfilling the ITU-R requirements for IMT-Advanced. One of the main assumptions made by 3GPP is related to backwards compatibility:
a Release 8 E-UTRA terminal must be able to work in an Advanced E-UTRAN; and
an advanced E-UTRA terminal can work in a Release 8 E-UTRAN.
In order to meet the backwards compatibility requirements, carrier aggregation is being considered as the method to extend the bandwidth in LTE-A system. The principle of carrier aggregation is shown in FIG. 1 (N×LTE Rel-8 BW).
Channel aggregation as shown in FIG. 1 can be seen as multi-carrier extension of LTE Rel-8. From the UL/DL control signaling point of view, the most straightforward multi-carrier concept is just to duplicate the existing Rel-8 control plane (PDCCH, PUCCH, . . . ) to each component carrier (or chunk). The principle of this approach is illustrated in FIG. 2, which shows an example of UL/DL control/data arrangement in the following use case:
one Rel-8 UE being allocated into one of the component carriers (1xPDCCH, 1xPUCCH); and
one LTE-A UE having DL allocation in two different component carriers (2xPDCCH, 2xPUCCH).
There are clear advantages related to this type of control signaling arrangement, including minimal standardization impact, support for non-continuous frequency spectrum, support for variable size component carriers and automatic support for frequency domain link adaptation and HARQ per component carrier
However, and as will be discussed in greater detail below, at least some problems that arise with this type of signaling arrangement relate to UL operation. The issue that is presented is how to best optimize the UL control signaling in the case when multiple component carriers are scheduled for a single UE.